Many different types of catheters are used for various diagnostic and therapeutic procedures. One type of catheter has an elongated flexible shaft with a steerable distal end for negotiating a path through the vascular network or other passageway in the body of a patient. These long and flexible catheters are well-suited for non-invasive procedures. Another type of catheter has a rigid shaft and is useful for invasive procedures where a more local opening or direct access to a treatment site is available.
While rigid catheters may be useful in some applications, they have certain limitations as well. For example, without a shape especially adapted for reaching a particular location in the body of a patient, the rigid nature of the catheter limits the area of tissue that can be reached and treated by the catheter. Even where a relatively large incision is provided, tissue areas that are not at least somewhat directly accessible cannot be reached. Although rigid catheters can include a curvable distal tip to facilitate their placement or their movement past obstructions, such a tip is relatively small and is not generally effective to compensate for the limited range of motion due to the shape of the catheter.
In one particular application, rigid catheters are used in the treatment of cardiac arrhythmias. Some invasive procedures for treating cardiac arrhythmias include positioning a rigid catheter with a deflectable distal tip through a local surgical opening against, or into, a chamber of the heart. Since the rigid catheter has a predetermined shape, one must select a catheter that has the most appropriate shape for positioning the distal tip of the catheter in contact with the treatment site in view given the particular anatomical pathway to be followed in the patient. It will be appreciated that a large inventory of rigid catheters may be required to accommodate the various treatment sites and patient anatomies. Further, for a patient having a relatively uncommon anatomic configuration and/or a difficult to reach treatment site, all rigid catheters of an existing set may well have less than optimal shapes for positioning the somewhat flexible treatment tip in suitable contact with their targeted site. This may impair the prospects of successfully carrying out the treatment procedure, especially when the treatment is one such as an ablation treatment that relies on good tissue contact and operates locally upon the contacted tissue. While a catheter having a customized shape might in theory be assembled or fabricated, in practice this would not be feasible during the procedure. Furthermore, for an ablation catheter which must bear against tissue at the remote region to ablate a lesion, the contour followed by the catheter in reaching the target site will in general further restrict the direction and magnitude of the movement and forces which may be applied or exerted on the tip itself to effect tissue contact and treatment.
It would, therefore, be desirable to provide a catheter which, while having sufficient rigidity to facilitate positioning of the catheter to a selected location within the body of a patient, is also better adapted to reach or treat the particular targeted anatomy of the patient.